Moulded from Grilamide TR90, a thermoplastic polyamide. Jello JL500 Black glasses are lightweight, extremely flexible yet super strong with 100% memory allowing the frames to bounce back to their original shape. The rounded oval lenses are rimmed in a black matte frame with vintage like key hole bridge. You'll love the look and feel of them. TR90 has demonstrated no risk of allergy and is FDA approved.